null、0 和 nothing 有什么区别? [英] What is the difference between null, 0 and nothing?

问题描述

null、0 和 nothing 有什么区别?

What is the difference between null, 0 and nothing?

我找不到解决所有这三个问题的问题.

I cannot find a question addressing all three of these.

例如:

如果我从 string 获取输入并将其解析为 int.

If I am getting input from a string and parsing it to int.

return Integer.parseInt(sc.nextLine());

或者，如果我问的是 string != "" 还是 不是什么，我很困惑何时以及为什么使用哪个.

Or if I am asking if a string != "", or a is not nothing I am confused about which to use when and why.

我对在验证数据时使用哪一个感到困惑.

I am confused about which one to use when validating data.

推荐答案

null 表示变量包含对不包含对象的内存空间的引用.

null means that a variable contains a reference to a space in memory that does not contain an object.

0 是数值为 0 的数据类型.

0 is a numeric data type with a value of 0.

Nothing 实际上并不存在，但是我认为您可能将其视为一个空字符串 ""，它只是一个 String不包含值的数据类型.

Nothing doesn't really exist, however I think you may be viewing this as an empty String "" which is simply a String data type that does not contain a value.

如果您从 Javascript 范式来看这可能会令人困惑.在 Java 中，变量不是真假，因此在比较时会考虑类型.

If your looking at this from a Javascript paradigm it may be confusing. In Java variables are not truthy and falsey therefore the type is considered in comparisons.

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